Wheat

Production, Properties and Quality

Wheat

Production, Properties and Quality

Edited by

W.BUSHUK Department of Food Science

University of Manitoba Winnipeg

and

v. F. RASPER Department of Food Science

University of Guelph Guelph

1t1l SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

First edition 1994 Reprinted 1996

© 1994 Springer Science+Business Media Dordrecht Originally published by Chapman & Hall in 1994 Softcover reprint ofthe hardcover lst edition 1994

Typeset in 1O/12pt Times by Type Study, Scarborough

ISBN 978-1-4613-6148-0 ISBN 978-1-4615-2672-8 (eBook) DOI 10.1007/978-1-4615-2672-8 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page.

The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made.

A catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: 94-70713

00 Printed on acid-free text paper, manufactured in accordance with ANSIINISO Z39.48-1992 (Permanence of Paper)

Preface

Wheat provides over 20% of the calories for the world population of 5.3 billion persons. It is widely grown in five of the six continents. It is a highly versatile food product in that it can be stored safely for long periods of time and transported in bulk over long distances. In relative terms, it is reasonably priced; over the past quarter century, the inflation-adjusted price of wheat has been declining. Modern milling and baking technology required for the transformation of wheat grain into consumable baked products is available or accessible in all countries of the world. For these reasons, and because Canada is one of world's leading wheat producing countries, it seemed appropriate to include a major symposium on wheat in the scientific and technical program of the 8th World Congress of Food Science and Technology held in Toronto, Canada during September 29-0ctober 4, 1992.

In selecting the topics for the symposium on wheat, we attempted to cover a full range of subjects including economics and marketing, nutrition, grading, processing, constituent chemistry and functionality, biotech-nology, and safety of genetically modified wheat varieties. The major focus was on common hard (bread) wheats; separate papers were devoted to the unique characteristics and technological properties of common soft (biscuit) and durum (pasta) wheats. Each paper was presented by an acknowledged international expert.

This book provides a more permanent record of the papers presented at the symposium. Because of the wide range of disciplines and topics, the chapters vary somewhat in length and in detail, and the personal style of writing of the various authors has been retained as much as possible.

We would like to thank all of the authors for their diligence in preparing and submitting the manuscripts. We would also like to record our appreciation to Heather Delorme for retyping several of the chapters and organizing the materials for publication. We trust that this book will be useful to all who are interested in wheat.

W.B. V.F.R.

Series foreword

The 8th World Congress of Food Science and Technology, held in Toronto, Canada, in 1991 attracted 1400 delegates representing 76 countries and all five continents. By a special arrangement made by the organisers, many participants from developing countries were able to attend. The congress was therefore a most important international assembly and probably the most representative food science and technology event in that respect ever held. There were over 400 poster presentations in the scientific programme and a high degree of excellence was achieved. As in previous congresses, much of the work reported covered recent research and this will since have been published elsewhere in the scientific literature.

In addition to presentations by individual researchers, a further major part of the scientific programme consisted of invited papers, presented as plenary lectures by some of the leading figures in international food science and technology. They addressed many of the key food issues of the day including advances in food science knowledge and its application in food processing technology. Important aspects of consumer interest and of the environment in terms of a sustainable food industry were also thoroughly covered. The role of food science and technology in helping to bring about progress in the food industries of developing countries was highlighted.

This book is part of a series arising from the congress and including full bibliographical details. The series editors are professor M. A. Tung of the Technical University of Nova Scotia, Halifax, Nova Scotia, Canada; and Dr G. E. Timbers of Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada. The book presents some of the most significant ideas which will carry food science and technology through the nineties and into the new millennium. It is therefore essential reading for anyone interested in the subject, including specialists, students and general readers. IUFoST is extremely grateful to the organisers from the Canadian Institute of Food Science and Technology for putting together a first class scientific pro-gramme and we welcome the publication of this book as a permanent record of the keynote papers presented at the congress.

DrD. E. Hood (President, International Union of Food Science & Technology)

Contributors

W. BUSHUK Department of Food Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.

A. CURIONI Istituto di Biotecnologie Agrarie, Universita di Padova, Via Gradenigo, 6-35100, Padova, Italy.

T. DACHKEVITCH Istituto Sperimentale per la Cerealicoltura, Via Molina, 3-20079, S. Angelo Lodigiano, Italy.

A. DAL BELIN PERUFFO Istituto di Biotecnologie Agrarie, Universita di Padova, Via Gradenigo, 6-35100, Padova, Italy.

B. L. D'APPOLONIA North Dakota State University, Department of Cereal Science and Food Technology, Fargo, North Dakota 58105, USA.

H. F ARIDI Nabisco Brands Inc Tech Center, PO Box 1943, East Hanover, New Jersey 07936, USA.

P. FINNEY USDA-ARS, Soft Wheat Quality Lab, Wooster, Ohio 44691, USA.

C. GAINES USDA-ARS, Soft Wheat Quality Lab, Wooster, Ohio 44691, USA.

R. H. KILBORN Grain Research Laboratory, 1404-303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

J. E. KRUGER Grain Research Laboratory, 1404-303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

A. A. MACDONALD Grain Inspection Division, 900-303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

viii

R.R.MATSUO

F.MEUSER

w. R. MORRISON

B. T. OLESON

N. E. POGNA

K. R. PRESTON

G. S. RANHOTRA

v. F. RASPER

P. RAYAS-DUARTE

R.REDAELLI

H.J.SCHOCH

J. D. SCHOFIELD

W. SEIBEL

CONTRIBUTORS

Grain Research Laboratory, 1404--303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

Technische Universihit Berlin, SeestraBe 11, D-13353 Berlin 65, Germany.

Department of Bioscience & Biotechnology, Food Science Division, University of Strathclyde, 131 Albion Street, Glasgow G11SD, Scotland.

The Canadian Wheat Board, 423 Main Street, Winnipeg; Manitoba R3C 2P5, Canada.

Istituto Sperimentale per la Cerealicoltura, Via Molino, 3-20079, S. Angelo Lodigiano, Italy.

Grain Research Laboratory, 1404--303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

American Institute of Baking, 1213 Bakers Way, Manhattan, Kansas 66502, USA.

Department of Food Science, University of Guelph, Guelph, Ontario N1G2W1, Canada.

North Dakota State University, Department of Cereal Science and Food Technology, Fargo, North Dakota 58105, USA.

Istituto Sperimentale per la Cerealicoltura, Via Molino, 3-20079, S. Angelo Lodigiano, Italy.

Buhler Ltd., CH-9240, Uzwil, Switzerland

Department of Food Science and Technology, University of Reading, Whiteknights, PO Box 226, Reading RG62AP,UK.

Federal Center for Cereal, Potato & Lipid Research, Schuetzenberg 12, D-4930 Detmold, Germany.

K. H. TIPPLES

R.TOWNSEND

CONTRIBUTORS ix

Grain Research Laboratory, 1404-303 Main Street, Winnipeg, Manitoba R3C 3G8, Canada.

Pioneer Hi-Bred International Inc., Plant Breeding Division, 7300 NW 62nd Avenue, Johnston, Iowa 50131-0038, USA.

Contents

1 World wheat production, utilization and trade B.T.OLESON

1.1 Introduction 1.2 Wheat: a brief overview 1.3 Wheat classes/grades 1.4 Wheat production 1.5 Wheat producers 1.6 Wheat utilization 1. 7 Wheat stocks 1.8 World wheat trade 1.9 Wheat prices 1.10 Long term factors 1.11 Concluding comment References

1

1 1 2 2 4 5 6 7 8

10 10 11

2 Wheat: contribution to world food supply and human nutrition 12 G. S. RANHOTRA

2.1 Introduction 2.2 Utilization of wheat 2.3 Nutritional profile

2.3.1 Caloric contribution 2.3.2 Protein contribution 2.3.3 Fat in wheat-based foods 2.3.4 Dietary fiber 2.3.5 Vitamins and minerals

2.4 Conclusions References

12 12 14 14 15 16 17 19 23 23

3 Bread-wheat quality defined 25 K. H. TIPPLES, R. H. KILBORN and K. R. PRESTON

3.1 Introduction 3.2 Bread 3.3 Wheat quality

3.3.1 Hardness 3.3.2 Gluten strength 3.3.3 Protein content 3.3.4 Soundness

3.4 Methodology and approaches used to evaluate bread and bread-wheat

25 25 26 27 27 27 28

quality 28 3.4.1 Processing factors 29 3.4.2 Product factors 32

3.5 Bread-wheat quality - from whose point of view? 33 References 35

XlI CONTENTS

4 Classification and grading 37 A.A. MACDONALD

4.1 Introduction 37 4.2 Why grade grain? 37 4.3 Canadian grading system 38 4.4 Grade definitions and standards 39 4.5 Grading factors 39 4.6 Grading consistency 41

4.6.1 Standardized grading procedures 41 4.6.2 Selecting and training inspectors 41 4.6.3 Sampling methods 42 4.6.4 Standard equipment 42 4.6.5 Sanitation 42

4.7 Classification 43 4.7.1 Varietal registration 43

4.8 Cleanliness standards 44 4.9 Quality averaging 45 4.10 Objective versus subjective measurements 45

5 Recent developments in flour milling 47 H. J. SCHOCH

5.1 Introduction 47 5.2 General requirements 47

5.2.1 Lower production costs 47 5.2.2 Automation 47 5.2.3 Improved working conditions 48 5.2.4 Product control 48

5.3 Developments in equipment and processes 49 5.3.1 Screenroom 49 5.3.2 Mill 51 5.3.3 Quality assurance 54 5.3.4 Flour silo 55

5.4 Summary 57

6 Recent research progress in bread baking tecbnology 59

W. SEIBEL

6.1 Historical overview 59 6.2 Nutritional recommendations 60

6.2.1 Expanding the varieties of bread 60 6.2.2 Use of non-bread grains 61

6.3 Processing techniques 65 6.3.1 Milling technique 65 6.3.2 Developments in dough and breadmaking techniques 67 6.3.3 Computer-assisted baking machinery 67 6.3.4 Extrusion cooking 67 6.3.5 Freezing techniques 68 6.3.6 Sourdough procedure 69

6.4 Labeling of bread 69 6.5 Quality assurance standards - sensory evaluation 70 6.6 Convenience products 70 6.7 Summary 71 References 71

CONTENTS

7 Wheat proteins: structure and functionality in milling and breadmaking J. D. SCHOFIELD

xiii

73

7.1 Introduction 73 7.2 The importance of gluten proteins to breadmaking quality 74 7.3 Classification of gluten proteins 75 7.4 The nature of gliadin and glutenin polypeptides 77 7.5 Conformational structures of gliadins and glutenin subunits 83 7.6 The polymeric structure of glutenin 84 7.7 Gluten proteins in relation to breadmaking performance 87 7.8 Technological importance of wheat grain endosperm texture 91 7.9 Possible mechanisms of endosperm texture variation 92 7.10 Involvement of a starch granule surface-associated protein in endosperm

texture variation 93 7.11 Hypothesis for the molecular basis of endosperm texture variation in

wheat 97 7.12 Application of the knowledge base concerning friabilin 98 7. \3 Concluding remarks 98 References 99

8 Wheat carbohydrates: structure and functionality B. L. D'APPOLONIA and P. RAYAS-DUARTE

8.1 Introduction 8.2 Chcmical composition and structurc

8.2.1 Sugars and glucofructans 8.2.2 Starch

8.3 Gelatinization and pasting properties 8.4 Differential scanning calorimetry 8.5 Nuclear magnetic resonance (NMR) 8.6 Electron spin resonance (ESR) spectroscopy 8.7 Interactions

8.7.1 Protein-starch interactions 8.7.2 Lipid-starch interactions 8.7.3 Hcmicelluloscs (pentosans)

8.8 Functionality as related to bread products 8.8.1 Sugars and glucofructans 8.8.2 Starch 8.8.3 Pentosans

8.9 Effects of gamma irradiation on processing 8.10 Summary Refercnccs

9 Wheat lipids: structure and functionality W. R. MORRISON

9.1 Composition and distribution 9.1.1 Composition 9.1.2 Distribution in the caryopsis 9.1.3 Varietal differcnces and edaphic cffects 9.1.4 Redistribution of lipids in millstreams

9.2 Functionality 9.2.1 Lipolytic enzymes 9.2.2 Lipoxygenase

107

107 107 107 108 109 110 III 112 112 113 114 114 115 115 117 122 124 125 125

128

128 128 128 129 \30 \31 \31 132

xiv CONTENTS

9.2.3 Free and bound lipids - composition and properties 9.2.4 Lipid binding - older theories and observations 9.2.5 Lipid binding - current concepts 9.2.6 Starch-lipid interactions 9.2.7 Gas retention in dough

9.3 Summary References

10 Enzymes of sprouted wheat and their possible technological significance 1. E. KRUGER

10.1 Introduction 10.2 Western-style breads 10.3 Hearth and flat breads 10.4 Chinese steamed bread 10.5 Spaghetti 10.6 Noodles 10.7 Conclusions References

11 Soft wheat quality in production of cookies and crackers H. FARIDI, C. GAINES and P. FINNEY

11.1 Introduction 11.2 Evaluation of soft wheat flour 11.3 Factors affecting soft wheat quality 11.4 Critical factors in soft wheat quality for commercial bakers 11.5 Textural properties of cookies and crackers References

12 Durum wheat: its unique pasta-making properties R. R. MATSUO

12.1 Introduction 12.2 Durum wheat production area 12.3 Uses of durum 12.4 Durum wheat quality 12.5 Mineral constituents 12.6 Stickiness and cooking loss of spaghetti References

13 Wheat utilization for the production of starch, gluten and extruded products F. MEUSER

13.1 Introduction and overview 13.2 Physical characteristics of gluten proteins and starch fractions

13.2.1 Gluten formation from wheat proteins 13.2.2 Centrifugal separation of a wheat flour dough 13.2.3 Physical characteristics of wheat starches

13.3 Starch production from wheat flours 13.4 Extrusion cooking of wheat starches and wheat flours References

132 134 134 136 136 138 138

143

143 146 147 148 149 150 151 151

154

154 156 157 158 160 167

169

169 169 170 172 172 175 177

179

179 180 180 182 189 193 198 203

CONTENTS xv

14 Genetics of wheat quality and its improvement by conventional and biotechnological breeding 205 N. E. POGNA, R. REDAELLI, T. DACHKEVITCH, A. CURIONI and A. DAL BELIN PERUFFO

14.1 Breadmaking, pasta making and nutritional quality of wheat 14.2 The endosperm proteins of wheat 14.3 Genetics of wheat endosperm proteins

14.3.1 Thegliadins 14.3.2 High molecular weight (HMW) glutenin subunits 14.3.3 Low molecular weight (LMW) glutenin subunits 14.3.4 The D-zone omega gliadin 14.3.5 The soluble proteins

14.4 Protein composition and gluten quality for breadmaking 14.5 Protein composition and nutritional quality 14.6 New technologies for the improvement of wheat quality

14.6.1 In vitro tissue culture 14.6.2 Gene transfer in wheat 14.6.3 Hybrid wheats

References

15 Quality and safety implications of genetic manipulations of food crops R. TOWNSEND

15.1 Introduction 15.2 Safety of genetically engineered foods 15.3 Transposable clements 15.4 US government regulations 15.5 IFBe report References

Index

205 206 208 209 212 213 214 214 215 217 219 219 220 221 221

225

225 225 227 22H 229 231

232